Ligand-Enhanced Abiotic Iron Oxidation and the Effects of Chemical versus Biological Iron Cycling in Anoxic Environments
Abstract
This study introduces a newly isolated, genetically tractable bacterium (Pseudogulbenkiania sp. strain MAI-1) and explores the extent to which its nitrate-dependent iron-oxidation activity is directly biologically catalyzed. Specifically, we focused on the role of iron chelating ligands in promoting chemical oxidation of Fe(II) by nitrite under anoxic conditions. Strong organic ligands such as nitrilotriacetate and citrate can substantially enhance chemical oxidation of Fe(II) by nitrite at circumneutral pH. We show that strain MAI-1 exhibits unambiguous biological Fe(II) oxidation despite a significant contribution (~30–35%) from ligand-enhanced chemical oxidation. Our work with the model denitrifying strain Paracoccus denitrificans further shows that ligand-enhanced chemical oxidation of Fe(II) by microbially produced nitrite can be an important general side effect of biological denitrification. Our assessment of reaction rates derived from literature reports of anaerobic Fe(II) oxidation, both chemical and biological, highlights the potential competition and likely co-occurrence of chemical Fe(II) oxidation (mediated by microbial production of nitrite) and truly biological Fe(II) oxidation.
Additional Information
© 2013 American Chemical Society. ACS AuthorChoice. Received: March 22, 2012. Revised: February 6, 2013. Accepted: February 12, 2013. Published: February 12, 2013. We thank Jim Morgan for many insightful conversations and inspiring S.H.K. to pursue this project, Sean Crowe, CarriAyne Jones, Arne Sturm, Sulung Nomosatryo, David Fowle, and Don Canfield for sample acquisition and fieldwork in Indonesia, Nathan Dalleska and the Caltech Environmental Analysis Center for instrumentation that benefited this project, Andreas Kappler, Nicole Klüglein, and Jay Labinger for helpful discussions, members of the Newman Lab and the anonymous reviewers for constructive criticism that improved the manuscript. This work was supported by grants to D.K.N from the Dreyfus Foundation and the Howard Hughes Medical Institute (HHMI). D.K.N. is an HHMI Investigator. S.H.K. is an HHMI International Student Research Fellow. The authors declare no competing financial interest.Attached Files
Published - es3049459.pdf
Supplemental Material - es3049459_si_001.pdf
Files
Name | Size | Download all |
---|---|---|
md5:40b424d85d76b075ccd6f335025b58f1
|
755.8 kB | Preview Download |
md5:d048e938719d3bd05dd1acb421222482
|
991.0 kB | Preview Download |
Additional details
- PMCID
- PMC3604861
- Eprint ID
- 38149
- Resolver ID
- CaltechAUTHORS:20130429-093249361
- Camille and Henry Dreyfus Foundation
- Howard Hughes Medical Institute (HHMI)
- Created
-
2013-04-29Created from EPrint's datestamp field
- Updated
-
2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences